World Population by Religion

According to a recent study (based on the 2010 world population of 6.9 billion) by The Pew Forum, there are:

2,173,180,000 Christians (31% of world population), of which 50% are Catholic, 37% Protestant, 12% Orthodox, and 1% other.

1,598,510,000 Muslims (23%), of which 87-90% are Sunnis, 10-13% Shia.

1,126,500,000 No Religion affiliation (16%): atheists, agnostics and people who do not identify with any particular religion. One-in-five people (20%) in the United States are religiously unaffiliated.

1,033,080,000 Hindus (15%), the overwhelming majority (94%) of which live in India.

487,540,000 Buddhists (7%), of which half live in China.

405,120,000 Folk Religionists (6%): faiths that are closely associated with a particular group of people, ethnicity or tribe.